In the related art, as a position detecting device for detecting a relative position between two members whose positional relationship varies, a position detecting device is known which includes a magnet and a magnetic sensor for detecting a change in magnetic flux generated by a detection target entering between the magnet and the magnetic sensor.
For example, a position detecting device disclosed in U.S. Patent Application Publication No. 2003/0117000 (Reference 1) includes a housing having a pair of arm units which are arranged facing each other, and a magnet and a magnetic sensor which are arranged at two positions apart from each other by being separately held in the respective arm units. For example, the position detecting device is disposed in a vehicle seat sliding device. A configuration is adopted in which the position detecting device functions as a seat position sensor for detecting a relative position of two sliding rails sliding in an extending direction thereof, that is, a seat sliding position.
That is, the housing in the position detecting device is fixed to any one of the sliding rails. For example, a detection target formed of a magnetic material, such as a plate-shaped member made of iron-based metal is disposed in the sliding rail on the other side. Furthermore, the detection target is arranged at a position where the two sliding rails configuring the seat sliding device relatively move so as to cause the detection target to enter and exit between both the arm units of the housing. In this manner, based on a change in the magnetic flux detected by the magnetic sensor, the position detecting device can detect whether the seat sliding position is located either at a first position (for example, a front position) where the detection target enters between both the arm units of the housing, or at a second position (for example, a rear position) where the detection target does not enter between both the arm units.
This position detecting device has a problem in that a foreign substance (magnetic body) attracted by a magnetic force of the magnet may adhere to the housing. Then, the foreign substance enters between the magnetic sensor and the magnet, thereby causing a possibility of erroneous detection.
In view of this point, the above-described position detecting device in the related art is provided with the housing, specifically, a cover for covering an opening between both the arm units. This cover prevents the erroneous detection caused by the entering foreign substance.
However, the above-described technology in the related art adopts a structure in which the detection target pushes and opens the cover member when entering a detection position set between both the arm units. Consequently, when the detection target comes into contact with the cover member, there is a possibility that a contact sound or abrasion powder may be generated. A problem also arises in that providing the cover member may increase the manufacturing cost. In this regard, the above-described technology has room for improvement.